A drug made from the sea squirt may help those with a form of cancer, a study in The Lancet Oncology suggests.
The sea squirt contains microbes which produce the active compounds
Just over half of a study of 51 patients with a type of soft tissue sarcoma responded positively to treatment with the drug Trabectedin.
Two patients treated with the drug saw their tumours disappear completely, while others saw their tumours shrink.
Soft tissue sarcoma is a rare form of cancer, and the type examined in the study represents just 10% of the cases.
Lead researcher Federica Grosso said for those with myxoid liposarcomas in particular, the drug offered hope.
Microbes that live within the sea squirt produce certain compounds which have been extracted to produce the drug.
All patients were treated solely with Trabectedin.
At six months, nearly 90% of those surveyed had not seen their tumours grow, and the median period before the tumours started to grow again was 14 months - a great improvement on other treatment outcomes, researchers said.
"If the results of this analysis are reproduced in ongoing prospective studies, myxoid sarcoma would represent a uniquely sensitive subgroup to Trabectedin treatment in the heterogeneous family of soft tissue sarcoma," the authors wrote.
Dr Grosso added that they did not yet know why it worked, and that further investigation was needed.
About 1,350 soft tissue sarcomas, lumps which can develop in any of the soft connective tissues of the body, are diagnosed each year in the UK, compared for instance to over 42,000 breast cancers.
Myxoid sarcomas, which tend to be found in older patients, would account for around 135 of these cases.
Dr Emma Knight, science information manager at Cancer Research UK, said: "This early-stage research highlights the potential of tapping into Nature's resources for future cancer treatments.
"A much larger trial that compares two groups of patients - one treated with the drug and one not - will now be key to proving whether the humble sea squirt really can offer hope to people with cancer."